Chevrolet CHEVY VAN G10 SERIES Service Manual page 172

3. Add the liquid p o rtio n (No. 1) o f the cooling system
cleaner.
4. Fill the cooling system w ith w ater to a level o f ab o u t 3
inches below the to p o f the overflow pipe.
5. Cover the radiator and run th e engine at m oderate speed
until engine coolant tem p eratu re reaches 180 degrees.
6
. Remove cover from radiator and continue to ru n the
engine for 20 m inutes. Avoid boiling.
7. While the engine is still running, add the pow der p o rtion
(No. 2) o f the cooling system cleaner and continue to run
10
the engine for m inutes.
W A R N IN G : Be careful not to scald your hands.
8
. A t the end o f this tim e, stop the engine, w ait a few
m inutes and th e n open th e drain. Also, remove lower
hose connection.
N O T E : D irt and bugs may be cleaned o u t o f the
radiator air passages
pressure fro m the back of the core. Do not bend
radiator fins.
Reverse Flushing
Reverse flushing should always be accom plished after the
system is thoroughly cleaned as ou tlin ed above. Flushing is
accom plished through the system in a direction opposite to
the norm al flow. This actio n causes th e w ater to get behind
the corrosion deposits and force th em out.
Radiator
1. Rem ove the radiator u pper and low er hoses and replace
th e radiator cap.
2. A ttach a lead-away hose at the to p o f th e radiator.
3. A ttach a new piece o f hose to th e radiator outlet
connection and insert th e flushing gun in this hose.
4. C onnect th e w ater hose o f th e flushing gun to a water
o u tlet and th e air hose to an air line.
5. T urn on the w ater an d when th e radiator is full, tu rn on
th e air in short blasts, allowing the radiator to fill
betw een blasts o f air.
C A U T IO N : A p p ly air
radiator will stand only a lim ited pressure.
6
. C ontinue this flushing un til th e w ater from th e lead-away
hose runs clear.
Cylinder Block and Cylinder Head
1. With th e therm o stat rem oved, attac h a lead-away hose to
th e w ater pum p inlet an d a length o f new hose to the
w ater o u tlet conn ectio n at th e to p o f th e engine.
N O T E : Disconnect
connections at engine when reverse flushing engine.
2. Insert the flushing gun in th e new hose.
3. T urn on the w ater and w hen the engine w ater jack et is
full, tu rn on th e air in short blasts.
by blowing out w ith air
gradually as a clogged
the heater hose and cap
Fig. 4 —Pressure Checking Radiator Cap
4. C ontinue this flushing until th e w ater from th e lead-away
hose runs clear.
Heater Core
1. Remove w ater o u tlet hose fro m h eater core pipe.
2. Remove inlet hose from engine connection.
3. Insert flushing gun an d flush h eater core. Care m ust be
taken w hen applying air pressure to prevent damage to
th e core.
Fan Belt Adjustment
1. Loosen bolts at D elcotron m ounting.
2. Pull D elcotron aw ay from engine un til desired tension
reading is o btained w ith a strand tension gauge. Refer to
" Engine Tune Up S pecifications."
3. Tighten all D elcotron bolts securely.
Radiator Cap
The rad iato r cap should be washed w ith clean w ater and
pressure checked at regular tune-up intervals. Inspect rubber
seal on cap for tears or cracks. Install rad iato r cap on tester
(Fig. 4). If th e pressure cap will n o t hold pressure or does not
release at the proper pressure, replace the cap.
Thermostat
The th erm o stat consists o f a restriction valve actu ated by a
therm ostatic elem ent. This is m ou n ted in the housing at the
cylinder head w ater o u tle t above the w ater pum p. T herm ostats
are designed to open and close at predeterm ined tem peratures
and if n o t operating properly should be rem oved and tested as
follows:
Replacement
1. Remove rad iato r to w ater o u tle t hose.
2. Remove th erm o stat housing bolts and remove water
ou tlet and gasket from th erm o stat housing (Fig. 5).
3. Inspect th erm o stat valve to make sure it is in good
condition.
4. Place th e rm o stat in a 33% glycol solution 25° above the
tem perature stam ped on the th erm o stat valve.
ENG INE C O OLING 6K-3
C H E V Y V A N SH O P M A N U A L